Recreational Water Concerns
Can water containing blue-green algae blooms be used for recreational activities?
Because local health officials cannot easily determine when blue-green algal toxins
are being produced, anyone considering recreation on or in the water should use
common sense. Simply put, if a scum-layer or floating mat is present, do not recreate
in or on that water. The chance for health effects is greater if you or your children
participate in water-related activities such as swimming, wading, water or jet-skiing,
or wind surfing. Try to find areas where a blue-green algae bloom is not present.
Is it safe to let your children or pets swim in ponds (e.g., farm ponds, stormwater
detention ponds, golf course ponds)?
By design, many farm ponds, golf course ponds, and stormwater detention ponds are
constructed to trap nutrients, eroded soil, and other debris. By doing so, they
prevent such materials from reaching nearby lakes, ponds, and streams. But because
more nutrients may be available and because these types of ponds are generally more
shallow and warm, it is possible for them to experience more frequent blue-green
algae blooms (which may produce toxins). Again, a common sense approach is recommended
for such ponds: if a scum layer or floating mat is present, do not let your children
or pets swim.
Is there a risk to SCUBA divers who swim in blue-green algae blooms?
It may not always be possible to avoid swimming in blue-green algae blooms. Rescue
SCUBA divers may be required to swim in areas where a bloom is present. In those
cases, divers should try to minimize the ingestion of water during the course of
the dive. Divers should also shower or rinse off thoroughly after exiting the water,
and clean all gear after use. Divers who show any signs of illness after exposure
should seek medical attention.
Do blue-green algae pose a risk to competitive swimmers such as triathletes?
When organizers establish the schedule and pick a course for a triathlon, they have
no way of knowing whether or not a blue-green algae bloom will be present in the
swim area. To the degree possible, race organizers are encouraged to establish a
course that minimizes the exposure of participants to blue-green algae blooms. Race
organizers may also want to consider having a rinse station established near the
swimming finish area. All participants are encouraged to minimize the ingestion
of water during the course of the event. As is the case in any organized race, participants
should seek medical attention if they show any signs of illness during or after
Fish Consumption Concerns
Can I eat fish from water containing blue-green algae?
Some blue-green algal toxins have been shown to accumulate in the tissues of fish
and shellfish, particularly in the viscera (liver, kidney, etc.). Whether or not
the accumulation levels are sufficient to pose a risk to humans is uncertain, although
it would depend in part on the levels of consumption and on the severity of the
blue-green algae blooms where the fish or shellfish were caught or collected.
The World Health Organization advises that people who choose to eat fish taken from
water where a blue-green algae bloom is present eat such fish in moderation and
avoid eating the guts of the fish, where accumulation of toxins may be greatest.
Also, take care to not cut into organs when filleting the fish and rinse the fillets
with clean water to remove any liquids from the guts or organs before freezing or
Important Note About Hygiene
All natural surface waters contain bacteria, algae, viruses, and other pathogens
that if consumed may pose health risks to humans, pets, and other domestic animals
(e.g., cattle, swine). No one should ever ingest raw water.